In recent years, input apparatuses having input units in the form of a plate for receiving inputs by pressure such as touch panels, touch switches and the like are popularly used as input units for receiving input operations by the user in information equipments, home electric appliances and the like. Such input units have a variety of types, such as resistive film type, capacitive type and the like. All of these input units are for receiving pressure inputs by fingers and stylus pens and, unlike push-button switches, they are not displaced even when being pressed.
Therefore, an operator cannot obtain feedback when the pressure input is received by the input unit. As a result, when using the input apparatus having the touch panel, for example, the operator is likely to input erroneously by tapping multiple times on the same spot, which may be stressful for the operator.
As methods to prevent such erroneous inputs, there are known methods for visually or auditory confirming the input operations by, for example, generating sounds or by changing a display state, such as colors of input objects such as input buttons and the like graphically displayed on a display unit, correspondingly to a pressured area upon reception of the pressure inputs.
However, such auditory feedback may be difficult to be confirmed in a noisy environment and is not applicable when the equipment being used is in a silent mode. In addition, in using such visual feedback, if the input object displayed on the display unit is small, the operator may not be able to confirm the change in the display state, and particularly when the operator is inputting by a finger, a view of the input object is blocked by the finger.
There is also suggested a feedback method relying on neither the auditory nor visual sensation but instead generating a tactile sensation at operator's fingertip by vibrating the touch panel upon reception of an input thereon (for example, see Patent Documents 1, 2).